The inter-computer communications field, exemplified by local area networks, is a rapidly expanding area of technology within the larger sphere of information processing. Local area networks provide for the interconnection of two or more computers separated by small to substantial distances ranging, typically, from several meters up to 2 kilometers.
Local area networks, however, may do more than just serve as communications links. They may act to make the resources of each participant available to all others. In ring and linear topology networks, for example, a common network media is shared between all of the computers participating in the network. The media itself is often no more than a coaxial cable or the equivalent. Each computer interfaces to the network via a communications node. While each computer may be distinctly different from any other on the network, the communications node functions to process raw data from its associated computer into a standardized format, often described as a data packet, and transmit it over the shared media. Data packets are also received by the communications node and provided to its associated computer after processing the packet to recover the raw data. Consequently, cooperative operation and the sharing of resources characterize local area networks.
The functional requirements placed on local area networks are numerous and often subject to tradeoffs depending on the particular circumstances involved in the implementation of the network. Some of the functional requirements, however, are relatively universal. While many computers may be participating in the network, only a single computer may be validly transmitting information over the network to one or more receiving computers at a time. Thus, the speed or transmission bandwidth of the network as a whole needs to be as great as possible.
Along with high speed, the network itself must be reliable. That is, first, the network must reliably provide for the transfer of data between computers without loss or distortion. Second, the network must be reliable in that, as a shared resource itself, any component failure within a communicatios node of the system should have a minimal if not undetected impact on the operation of the network as a whole.
Additionally, the cost of the network system, including the network media and the component systems forming each communication node, must be as low as possible, as a practical matter, while still obtaining the necessary speed and reliability of the local area network system.